Two Power Sources, One Bus

[eepup]

I am interested in finding a solution to the following problem I have encountered at a medium sized industrial plant and would really appreciate any help or expertise:

The plant has a utility feed and a proposed new 1MW solar power system that cannot be interfaced into the utility grid (the utility company will not accept the solar power). I am trying to figure out a way to maximize the use of this 1MW Solar Power System feed. Here is a little background...the solar system output power is inverted and stepped up to 12kV for a long cable run. At the end of the cable run, it is stepped down via a 1000KVA 12kV/480V transformer and is available to power what is envisioned as dedicated "solar powered" 480V MCC lineup. The most obvious problem to me is that there are not many loads at the plant that only need to be on during the day (i.e. when the solar system is generating power). Switching the "solar powered MCC" to plant 480V power at night solves that problem. Great, but this “solar powered MCC” would be all or nothing. The solar system’s power output is somewhat of a bell shaped curve and, in the morning, the system will take hours to reach the amount of output amps to switch the MCC to solar power and conversely, in the afternoon, the output amps will dwindle below a threshold level and not be able to power the MCC. This system will not have a battery bank so therefore the plant will miss out on the bookends of output power curve. Without being able to use every available amp from the solar system, the economics of the project will fall far short of initial expectations. Having a complex (automated) switching scheme to toggle smaller breakers in the “solar powered MCC” between solar and utility power would be a dizzying undertaking (not to mention the fact that it would require separate buses in the “solar powered MCC”).

In short, does anyone know of a “black box” product that could accept two incoming 480V power feeds (in this case, solar power and utility power) and output a single power source? Ideally, such a product could be configured so that it uses the solar power feed primarily and would add utility power to make up the balance of the plant demand.

Any help or leads will be most appreciated!

 

[rasor1514]

I don't know of a black box that would do this, but I am curious why the utility would "not accept the solar power."
Is this a U.S. utility?

 

[MJJBEE]

what is the total usage of the plant? If it's more then 1 MW then you could use it to run the plant bus and not back feed into the utility. You might also have to corect the powerfactor to avoid poor powerfactor charges.